1. Technical Field of the Invention
The present invention relates to a surveillance video camera, and more particularly to a surveillance video camera to be operative in combination with a surveillance system for watching an object such as for example unqualified people and other intruders, and adapted to take an image indicative of the object at a relatively high quality without being affected by an illumination intensity.
2. Description of the Related Art
Up until now, there have been proposed a wide variety of surveillance video cameras of this type one typical example of which is disclosed in Japanese Patent Laying-Open Publication No. H08-307774 (paragraph 0026, FIG. 1).
The above mentioned conventional surveillance video camera comprises three image sensors for respectively sensing color component images collectively indicative of an object to selectively take sensitivity enhancing modes such as for example a long exposure mode and a pixel synthesis mode.
In order to enhance the sensitivity of the image sensor, the exposure period of the image sensor is generally extended in reduced illumination. However, the resolution of the motion of the object is deteriorated by reason that the field number of the images to be taken per unit time are decreased when each of the images is taken over the extended exposure period. In the pixel synthesis mode, the image can be taken at relatively high quality by reason that the color components respectively sensed by the image sensors are not mixed with each other.
On the other hand, in the single image sensor type-surveillance video camera, the image cannot be taken at relatively high quality by reason that the color components sensed by the image sensor are mixed with each other. It is, however, not always essential that the image can be taken in color in reduced illumination such as for example a night.
The conventional surveillance video camera thus constructed as previously mentioned, however, encounters such a problem that the three image sensors type is not simple in construction, and produced at a relatively expensive cost in comparison with single image sensor type.